This invention relates to sensor-assemblies for engines.
The invention relates especially, though not exclusively to thermocouple sensor-assemblies having a plurality of thermocouple-probes extending radially from a central hub. Thermocouple sensor-assemblies of this type are used in gas-turbine engines for measuring the temperature of gas emerging from the jet pipe. The hub of the assembly is mounted on the central exhaust-cone within the jet pipe, with the probes extending into the exhaust-gas stream at spaced positions around the cone. The thermocouple wires are electrically interconnected in parallel with one another in the hub so that their common output provides an average measure of the exhaust-gas temperature.
In known forms of thermocouple-probe assemblies external electrical connection to the probes is made by the use of a junction box within the hub of the assembly. This arrangement, however, suffers from the disadvantage that the weight of the junction box adds significantly to the overall weight of the assembly. Alternatively, external electrical connections to the probes in such an assembly have been made by joining conductors of an external cable directly to the thermocouple wires, by, for example, welding. Although this arrangement can be relatively light in weight, it has the disadvantage that the connections are more liable to damage caused by vibration during operation of the engine and it is more difficult to remove the probes for maintanance or replacement.